Speaker
Mr
Juan Miguel Carceller
(University of Granada)
Description
The Pierre Auger Observatory is the largest detector of ultra-high energy cosmic rays (UHECR) built so far. With the Fluorescence Detector (FD) of the Auger Observatory, a direct measurement of the depth of maximum of shower profiles, $X_{\rm max}$, is performed using the ultraviolet light emitted by nitrogen as the shower develops in the atmosphere. With data on $X_{\rm max}$ collected during more than a decade of operation we report on the inferences on the mass composition of UHECRs in the energy range $E=10^{17.2}-10^{19.6}$~eV and on the measurements of the proton-air cross section for energies up to $10^{18.5}$~eV. The FD operates only during moonless nights and has a duty cycle of around 15\%, thus to gain a larger statistics other mass sensitive observables measured with the Surface Detector (SD), having almost 100\% duty cycle, can be used. Here we present the results on $X_{\rm max}$ (SD) obtained using the information on the particle arrival times recorded by the SD stations allowing us to extend the $X_{\rm max}$ measurements up to $10^{20}$~eV. The inferences on mass composition, in particular using the data of the SD, are subject to systematic uncertainties due to uncertainties in the description of hadronic interactions at ultra-high energies. We discuss this problem with respect to the properties of the muonic component of extensive air-showers as derived from the SD data.
Primary author
Mr
Juan Miguel Carceller
(University of Granada)
